Recent progress of PureCsI+APD readout2009 July 7thNatsuko Maeda/Kenkichi MiyabayashiNara Womens UniversityBelle-II calorimeter meeting

OutlineIntroductionMotivationHamamatsu S8664-series APD.Set up of cosmic test.ResultsTypical eventPulse height spectrumEquivalent noise energyFurther check pointsSummary and plan

MotivationPureCsI+PhotoPentrode option (baseline)Design based on the technologies as of 2002, 7 years ago.Why not revisit recent progress of devices and materials?Photon sensor; Large area(1cm2) APD.Scintillating crystal; BSO separate talks.

Hamamatsu S8664-1010 APDActive area : 1cm1cm.Quantum Efficiency 35~40% @300nm.Typical gain : 50.S8664-1010(Taken from Hamamatsu web page)Taken from Dr. J.Kataokas pptwavelengthQ.E.

Counter preparationReal size pure CsISmall board with APD(optical contact:grease) PreampHV lineSignal cable

Set up of cosmic testPure CsIPreamp.HVShaper(30ns)FADC(12bits,43MHz)CAMACmoduleCoincidenceDigital Oscilloscope(ch.2: trigger).Analog outDigital Oscilloscope(ch.1)APDCosmic ray

They are inside thermostatic box.Triggers kept at 25 deg.C.

An cosmic event exampleon the oscilloscope2s

How to obtain equivalent noise energy(E.N.E.)Noise level in FADC counts;Obtained by the width of the pulse height spectrum peak obtained by test pulse.

Energy scale determined by cosmic rays;Transversely passing through M.I.P. ~30MeV.

Fit to obtain pulse heightn=5; shaper circuit a=pulse heightt0=pulse start time=timescale Test PulsePedestal

Pulse height spectrum for test pulseNoise level is obtained to be ~8 FADC counts.

Same thing repeated; cosmic data +PedestalA typical event

Cosmic pulse height spectrumAverage pulse height obtained to be ~120 FADC counts.PureCsI+S8664-1010HV=455V

Equivalent noise energy(E.N.E)30 MeV X (8/120) = 2 MeV.Even 2 APDs are attached, down to 1.4 MeV.Still significantly higher than required level.

Further check pointsDependence on applied voltage, temperature, APD piece-by-piece variation to be measured.S8664-1010 typically at 25 deg.C,Gain X50 at ~420V.Breakdown at ~470V.Now 455V is applied.long term stability test needed at such voltage.

Summary and planPureCsI+APD(S8664-1010) cosmic test going.455V applied.E.N.E. is ~2MeV; still higher than required.HV, temperature dependence, piece-by-piece variation to be tested.

Same kind of test to be repeated with BSO.Borrowed reference crystal; 2.2X2.2X18cm3.Mechanical attachment to be designed/ordered soon.Narrower trigger counters to be prepared as well.

Items & schedule toward decision 2009 Dec. in KMs mind2X2X20cm3 4pieces test.prod.L.O. check(&Rad. Hard.)Belle-II General MeetingRad. Hard. by small sample.G4 (simple) simulationMechanical structure (crash test as well?)Cosmic test Ref.BSO+APDCosmic testPureCsI+APD Temp., HV, Seek further improve,Test temp.-feedback HV.L.O. by small sample Start up.(?)Event generation & anal.HV supply system,Monitor system,etc.,Tomoko IwashitaNatsuko MaedaKMAs of 20090707

JulyAug.Sep.Oct.Nov.Dec.

**